The invention relates to a sound reproducing arrangement for artificial reverberation in which a plurality of loudspeakers are arranged within an enclosed space. The loudspeakers are connected to associated microphones via amplifiers, and the loop gain of each of the systems constituted by an associated microphone, amplifier and loudspeaker is small relative to one.
Such an arrangement is inter alia, described in British Pat. No. 1,259,512. Its operation is based on the following: It is assumed that in said space an audio source is present which is independent of said arrangement, for example one or more speakers, an orchestra or the like. A microphone, which is suspended at a specific location in said space, picks up the sound at said location and, after amplification, produces a corresponding sound signal in the associated loudspeaker. The system: microphone, amplifier, and loudspeaker thus functions as a sound-reinforcing reflector of the sound at the location of the microphone, which makes the impression on the audience as through a number of sound reinforcing walls were placed in said space. As the sound always requires a certain time delay to reach the microphone from the sound source and subsequently to reach the audience from the loudspeaker, this corresponds to a specific reverberation time and the entire system may therefore be referred to as an "artificial reverberation system". However, in order to obtain a satisfactory effect a large number, for example 50 to 100, of such systems are necessary.
It is an object of the invention to improve the known arrangement. Until now it was believed that in order to avoid acoustic instabilities the microphone had to be placed at a substantial distance, for example at least a few meters, from the loudspeaker associated with the same system so that, as a result of this distance between microphone and loudspeaker, the loop gain in the system would remain small relative to one. However, in view of the large number of systems required, this leads to an extremely intricate cabling of the entire arrangement. Moreover, this may give rise to the effect that at some locations the sound from some of the loudspeakers is received sooner than that from the independent sound source, which adversely affects a natural reproduction.